Do vitamin D and protein synergise with physical activity to enhance musculoskeletal health across ageing: a complex intervention.

Aim: To conduct a complex RCT to determine the effects of vitamin D and protein supplementation on muscle mass, function, and systemic inflammation against a background of enhanced physical activity.

Experimental plan:
1) We will recruit 120 non-sarcopenic adults across two strata: 60 approaching older age (50-65yrs) and 60 older adults (65-75yrs)
2) Volunteers will be randomised (stratified by age) to receive an iso-caloric placebo or treatment (25µg/d vitamin D and 20g whey protein/3xd) for 12 weeks. All volunteers will take part in a physical activity promotion programme.*

*The exact interventions will be optimised for maintenance of muscle mass without impact on appetite during the MRes phase. Volunteers consuming dietary supplements or with high physical activity will be excluded.

Measurements at weeks 0 and 12: body composition (BIA), musculoskeletal/physical function (handgrip strength, TUG, SPPB, isokinetic strength), dietary intake (food diary), physical activity (accelerometry and self-reported), vitamin D status and systemic inflammation (IL6 and CRP). Samples will be stored for future biomarker analysis.

Training: The student will receive training in the design and execution of diet and lifestyle interventions. This includes adherence to research ethics/governance, study design, GCP and statistical analysis. The student will receive specific training in designing physical activity programmes, assessment of muscle mass and function, dietary assessment, analysis of 25(OH)D, physical activity and body composition. More generic training will be recognised through a training needs analysis and will be met through the MRes training programme and the Sheffield Doctoral Development Programme.
Interaction: In addition to the immediate supervisors an advisory panel will be drawn from the nutrition community at Sheffield and the broader CIMA community. The student will be included in the Food, Nutrition & Health Group (Sheffield) and the Human Nutrition Research Centre (Sheffield) activities and seminar programmes. The student will also be expected to attend and present at the CIMA annual meeting, allowing a further opportunity for interaction with CIMA members.
Co-supervision: Co-supervision will be achieved via formal monthly supervision sessions using Skype or teleconference, and face to face meetings every 6 months. The student will be expected to spend 3-4 weeks at Newcastle University in each year of the programme for training and joint supervisory purposes.